1. Field of The Invention
This invention comprises an apparatus and method for wrapping an annular object. More specifically, it relates to wrapping and sealing off the exposed surfaces of a large coil of sheet metal, e.g., steel, aluminum, copper, etc., thereby preventing rust and other deteriorations over extended periods of time while in storage or in transit. Such rusting is prevented in the present illustrative embodiments by wrapping all exposed surfaces of the coil with stretch wrap, a material well known in the industry. The wrapped surfaces include inside the xe2x80x9ceyexe2x80x9d (or hollow cylindrical center core) of the coil, formed when the sheet metal is originally wound around a mandrel. Although disclosed in terms of sheet metal coils, the invention is applicable to other annular objects including but not limited to coils of paper, cables, wires, hoses, chains, etc. Also, although disclosed in terms of stretch wrap under tension, the invention is applicable to other wrapping material dispensed from a roll, including but not limited to pre-stretched wrap, shrink wrap, paper wrap, cloth wrap, etc., and, in particular, stretch wrap treated with Vapor Corrosion Inhibitor (VCI) which also serves to preclude rust.
2. Background and Summary of the Invention
The need to seal annular steel coils by applying a wrap thereto is well known in the art. The following patents directed thereto are representative of those known to the inventors: U.S. Pat. No. 3,856,141 to Reed; U.S. Pat. Nos. 4,793,485 and 4,928,454 to Bertolotti; U.S. Pat. No. 5,282,347 to Clein; U.S. Pat. No. 5,501,058 to Sonoyama et al.; U.S. Pat. No. 5,755,083 to Clein et al.; U.S. Pat. No. 5,782,058 to Chadwick; U.S. Pat. No. 5,867,969 to Quinones; and U.S. Pat. No. 5,941,050 to Georgetti et al., the disclosures of which are all incorporated herein by reference. The necessity of wrapping steel coils and the difficulties to be overcome are detailed in these references and need not be repeated here.
So far as the present invention is concerned, the most pertinent of the prior art in this area are Clein and Clein et al., supra, helically wrap a rotating annulus by repeatedly passing a roll of wrapping material around successive radial portions of said annulus. These inventors have provided a wrapping apparatus comprising an endless oval track composed of two sections which are separated to allow insertion of a portion of the oval track through the hollow center core of the steel coil, after which the two sections are reunited. A self-propelled shuttle continuously travels around the resulting endless track. The shuttle carries a roll of wrapping material, which is applied to the slowly rotating coil as a long, continuous helical strip. A complex series of fixed and biased rollers are incorporated into the shuttle to maintain tension on the coil wrap, thereby increasing the size and complexity of the shuttle. While effective so far as prior inventions go, these patents have numerous and important disadvantages.
One major disadvantage of their disclosed systems is the complexity of the equipment, i.e., the track and supporting structure needed is large and cumbersome. Either the wrapping structure or the coil must be movable in order to be able to interleave the coil and the track. Clein, supra, prefers a movable trolley to support the coil, to transport it to and from the endless track, and to rotate it when in place; not an easy task in view of the size and weight of the coil, which by itself can weigh up to thirty tons. Clein et al., supra, move the coil on conveyer carriages from which they are lifted by drive rollers, an exceedingly complicated arrangement. Moreover, to house an endless track tall enough to handle the largest coils, both patents have resorted to cumbersome superstructures, several stories tall, that pose a potential physical hazard to overhead cranes.
A further disadvantage of both patents is the time required to wrap the coil. The endless track is of a fixed size, which remains the same regardless of whether the coil being wrapped is large or small; of necessity, the track has been designed to handle the maximum coil size contemplated for wrapping. Consequently, the time required for the shuttle to circle the track is at a maximum. Obviously, for smaller coils, the time wasted during each lap of the shuttle around the track accumulates into a good deal of time wasted for the wrapping the entire coil, and continues to accumulate when large batches of smaller coils are being wrapped.
Other disadvantages are inherent in their systems as well. For example, the aforementioned complex tensioning rollers on the shuttle to stretch the wrap are cumbersome and costly. They are also difficult to adjust and time consuming to reload when the wrap either runs out or is severed, e.g., due to adverse operating factors such as excessive tensioning of the wrap. Also, the operator of their systems must always return to the system console to select the next system command, which forces him or her to walk back and forth to the coil being wrapped and/or the next coil to be serviced.
The illustrative embodiments of the instant invention advantageously reduce the equipment needed to handle large coils, namely, down to a permanent work station with a coil roller capable of supporting and rotating a coil. This work station is serviced by a conventional overhead crane for lifting loading and unloading large coils.
In the illustrative embodiments, a plurality of such permanent work stations permit independent loading and unloading operations to be performed simultaneously, thereby increasing coil throughput and decreasing coil-to-coil processing time.
The illustrative embodiments further eliminate the need for a costly shuttle-track structure, which is both space-consuming and time-consuming, by adopting a less costly, space-efficient floor-mounted track system on which a pair of movable gantries travel in two directions. These gantries carry a pair of robotic wrapping mechanisms into precise position in a matter of seconds, both between the work stations and toward the coil loaded at each work station.
In accordance with at least one illustrative embodiment, a coil is wrapped and sealed solely by means of a pair of opposing robotic arms, whose movements are under variable control, in combination with a coil roller, which slowly rotates the coil about its cylindrical axis, and whose speed is also under variable control.
In accordance with at least one illustrative embodiment, a coil is completely wrapped and sealed by a pair of robotic arms passing a roll of wrapping material repeatedly through, and then around, each successive segment of the annulus of the coil as the coil is slowly rotated.
In accordance with at least one illustrative embodiment, the time needed to wrap said coil is minimized by adapting the range of vertical movements of the robotic arms to the height of the coil and by adapting the range of their horizontal movements to the width of the coil, based upon data collected via position and distance sensors, thereby adapting the xe2x80x9cwork envelopexe2x80x9d of travel for the robotic arms down to the size of any given coil.
In accordance with at least one illustrative embodiment, the time needed to wrap said coil is minimized by adapting the rotational speed of the coil roller to the height and the width of the coil, based upon data collected via position and distance sensors, thereby adapting the rotating device to the size of any given coil.
In accordance with at least one illustrative embodiment, a wide range of gauges, or thickness, of stretch wrap is accommodated by providing variable amounts of tension to the wrap via a simple, compact, continuously-adjustable tensioning device built into each handle holding the roll, which can be quickly and easily adjusted by the operator.
In accordance with at least one illustrative embodiment, the wrap mechanism operates under the complete, automatic control of an off-the-shelf PC via flexible computer programs that are easy to update, change, or replace, as compared to the more rigid structure and logic of traditional Programmable Logic Controllers (PLCs).
In accordance with at least one illustrative embodiment, the operator selectively controls the complex, automated processes of the computer programs via a hand-held wireless remote control, where each of the steps necessary to wrap a coil is initiated by a single button push on the remote control, allowing the operator to stand near the coil being wrapped and issue commands, or walk to the next station and load the next coil.
In the illustrative embodiments of the present invention, the difficulties described earlier are overcome while accomplishing the above objectives, by providing a novel coil wrapping apparatus which performs a novel wrapping method, including, in different combinations, the exemplary components and steps of: loading a coil of sheet metal on a variable-speed motor-driven coil roller which slowly rotates the coil, positioning a pair of adaptable opposing robotic arm mechanisms to face each other at opposite ends of the coil, dispensing wrapping material under operator-selectable tension generated by variable-tension handles, and programming the robotic arms to exchange the roll of wrapping material back and forth to each other while carrying the roll repeatedly through and around each radial segment of the annulus of the coil as it rotates. An associated enclosure houses the system electronic components, such as power supplies, computer control boards, motor drives, sensor interfaces, etc., under control of a central processing unit (CPU) within a personal computer (PC), all of which serving to control the coil wrapper.